The present invention relates generally to magnetic disk storage units, and more particularly to a magnetic disk storage unit with a magnetic head separating mechanism for separating a float type magnetic head from a magnetic disk.
In a conventional magnetic disk storage unit using a contact start and stop (abbreviated CSS hereafter) method, a float type magnetic head contacts a magnetic disk while the disk stops rotating, and floats therefrom by 0.4 to 0.5 .mu.m to write data thereon and/or read data therefrom as it rotates at a high speed of about 3000 to 3500 rpm and generates an air flow. However, this type of magnetic disk storage unit has the following disadvantages:
1. The disk in the disk storage unit under high temperature and high humid cannot be rotated because of an adhesion phenomenon which strikingly increases a coefficient of static friction.
2. Since a bulky and heavy spindle motor for rotating the disk with a large amount of torque against the static friction force is needed to start rotating the disk, the disk storage unit cannot be miniaturized and made light. In addition, such a motor makes the disk storage unit consume a large amount of power.
3. Since the disk rotates while contacting the head, until its rotating speed is high enough to create the air flow, the disk gets damaged because of a head crashing phenomenon related to dust, located between the disk and head, which scratches the disk and destroys data stored on it.
4. If a sensorless spindle motor which often inversely rotates during starting time is used, the head crashing phenomenon easily occurs.
Accordingly, a disk storage unit having either a cramping mechanism or a solenoid mechanism which respectively separates the head from the disk while the disk stops has been proposed, for example, by U.S. Pat. No. 4,933,785.
However, the above cramping mechanism proposed by U.S. Pat. No. 4,933,785 has a disadvantage in that the head often shakes because of a loose-jointed connecting part of the cramping mechanism; thus an edge of the head damages the disk when the head lands on the disk. Respectively, the above solenoid mechanism has disadvantages in that the solenoid generally actuates so quickly that each component of the head is impacted thus shortening the life of the head. If a damper mechanism or electrical feed back mechanism for absorbing impacts is provided, the disk storage unit is prevented from being simply constructed, miniaturized, and being made light and inexpensive.